Alternator charging voltage

[LFarmer]

I just noticed today that the gauge was showing well over 14 on the dash. Got out the volt meter and at idle it has 14. 82 volts. Is it just me or is that too high?

 

[CharlesHoward]

Mine pegs just over 14 too once the engine is warmed up.

 

[jelag]

Charging voltage is controlled to some extent by the outside temperature and what the ambient air sensor sees... . The colder the battery the harder it is to charge, and thus the need for a higher voltage... as the battery warms up it takes a lower voltage to charge it... So temperature plays a part... Also remember that this sensor is in the cold air intake... so it won't see much of engine temperature. .

Also you want a fully charged battery to crank in cold weather as the colder the temperature it is the more cranking amps it take to roll over a cold engine and the battery has less available current the colder it gets...

A fully charged battery will hardly freeze... well maybe at something like -50*F... but a dead battery will freeze and crack the case at 25*F.

Anyway, with the logic circuits available in a modern computer you might as well use it to adjust the charging voltage based on temperature... .

I've noticed as I cross the desert at 110* the charging voltage is below 14 and here in town with the outside temperature at something like 10*F right now I'm sure it would be closer to the 14. 8 mentioned above... .

BTW - years ago... charging voltage as high as 15. 5 was acceptable before the newer batteries and charging systems emerged on the market...

Hope this helps. .

 

[seafish]

Nothing really wrong with 14. 85 volts...

Did it used to be lower??

It's possible that your one or both of your batteries are beginning to fail and thus they are drawing a higher charging voltage. Have you checked your batteries with either a load tester or a hydrometer?

You can also check for sewelling of the battery case which is also a sign of overcharging from heat build-up...

I am sure that others here will chime in with even better ideas... let us know what you find out, though like I said, first I would check each of your batteries condition with a load tester or hydrometer. I personally prefer the batteruy hydrometer as it will tell you if a specific cell in the battery has gone bad. In fact, one bad cell will lead to overcharging of the pother cells... .

 

[LFarmer]

Thanks for the replies. What jelag said makes sense. It is unusual to have 5" of snow on the ground here and today's high is 31. I will load test the batteroes individually just to check because they are almost 5 years old.

 

[Hoefler]

Another thing to consider, if you just started it cold, the the grid heaters is a very high draw. It would take some voltage to restore the batteries after cranking and heating.

 

[AH64ID]

What jelag said is correct, but the temp sensor for the battery is under the drivers side battery.

 

[jelag]

Gosh, didn't know there was a second temperature sensor... . I thought they used the same senor as the ambient air senor like most of the cars do...

Thanks for the insight

 

[AH64ID]

Gosh, didn't know there was a second temperature sensor... . I thought they used the same senor as the ambient air senor like most of the cars do...

Thanks for the insight

Yep. You can actually watch the battery warm-up with the voltage. I think the extra monitoring is why the batteries last so long. But on the downside the alternator plugs into the pass battery and the temp is sensed on the drivers battery, so if your cross connection cable goes bad you can boil and destroy your pass battery pretty easily.

 

[TMutziger]

I've noticed the same 14+ voltage readings on mine. Batteries are less than a year old. Interestingly though, they got replaced because the passenger side one started to cook. I noticed a terrible smell in the cab and traced it to the battery. It was hot to the touch and I could hear it boiling. Maybe I should check the cross connection cable. The new batteries are fine though. Not doing it now.

 

[p-Bar]

I have a escort Radar detector and have it setup to monitor the voltage which runs as stated above 14. 81 also my Scan gauge II reads the same a lot higher than back in the day of 13. 8 volts. Seems like it would be hard on the batteries.

 

[AH64ID]

I had an 07 Tacoma that would run the same voltage as the Dodge for about an hour, then drop to a "float" voltage of mid-low 13's. I really thought that was a smart setup, but even if the Dodge runs for 6-8 hours straight the voltage never "floats".

 

[jelag]

One of the issues that can be a problem with this. . is charging a RV battery in a trailer... to get my batteries fully charged for 2 or 3 days of dry camping the way we use the trailer was to install an 8 gauge charge wire and ground... . from the battery to the trailer plug and from the trailer plug to the trailer...

A test before and after found that we picked up a full 1 volt at the trailer batteries doing this... . a huge improvement over the factory wiring that looks like its 14 gauge wire... .

 

[AH64ID]

Yeah I agree with you on that. I have found that if I leave my camper hooked up at home for 36-48 hours I get an extra day over what I get in a 2-3 hour drive just letting the truck charge it.